Among these pathologies chronic obstructive pulmonary disease (COPD) is the more important for number of patients and deaths affecting 80 million people in the world [WHO, 2006]. The time course of the disease is characterized by stable periods broken up by intermittent acute exacerbations of the symptoms, during which a severe inflammatory process occurs, leading to increased airways obstruction. During exacerbations the risk of death is very high [Connors et al, 1996;Soler-Cataluna et al, 2005]. Moreover the frequency and severity of exacerbations correlate with the worsening of the health condition of the patient [Anzueto et al, 2009; Donaldson et al, 2002].